Previous efforts have been made to reduce the gas/tar ratio, especially the CO/tar ratio, of the MSS of cigarettes. Among the chemical methods one may refer to different catalysts added to the cigarette to enhance carbon monoxide to carbon dioxide conversion, and among the physical methods one may refer to carbon filters. Embodiments of the present invention comprise a gas filter in which neither chemical reactions, nor chemical or physical additives nor absorbents are necessarily involved. The design of the cigarette gas filter can be optimized to increase the cigarette gas filter's efficiency while keeping the cigarette gas filter's effect on increasing the gas flow pressure drop acceptable.